1. Field of the Invention
The present invention relates to improvements in a combination key which permits the opening of various different locks with a single key.
2. Description of the Prior Art
Most conventional locks have a tumbler which is normally blocked and must be turned for opening. The tumbler is blocked by means of a key. More specifically, the tumbler has a lower structure with levers which must assume specific positions for the unblocking to occur, which positions are determined by the introduction of the key and through the appropriate contours on the operative edge or edges of the key. The turning of the tumbler may cause the taking along of the ward directly or may establish an electric circuit. This causes the actual opening without affecting the structure of the operative lock-key assembly.
Today's lifestyle require that often a certain person must carry a considerable number of keys to have access to different dwellings provided with corresponding locks. The ideal solution would be to have a single key for opening all locks, but it is clear that such a solution is not feasible because, unless all locks are installed at the same time, so that they can easily be identical, it would be very difficult and costly to later obtain one or more locks that would fit a certain key. On the other hand, losing the one and only key would, under certain circumstances, make it necessary to change all the locks which also would be a considerable economic problem.
The applicant is the owner of a recently granted U.S. Pat. No. 4,545,226 (application Ser. No. 566,523 of Dec. 29, 1983), relating to a combination key which overcomes these problems by permitting the use of a common key for different locks without crating a problem by the loss of the key since, without knowing its concrete combination, the key cannot be used for opening any of the locks for which it is intended.
Specifically, the combination key disclosed in patent application Ser. No. 566,523 includes a stem capable of insertion in a wide spectrum of locks, just as a conventional key matrix is able to fit into different locks, the teeth which are to establish the specific combination for each case being cut from the matrix. In accordance with the present invention, the teeth are independent of the stem and displaceable along the latter to vary their position in accordance with different locks.
Thus, starting with a stem of a certain configuration common for all locks of the spectrum, on the stem are installed a series of teeth in variable number, which only with a certain positional combination will permit the opening of a certain lock, while in any other position they would be ineffective for the lock. To effect the opening of another lock, it will suffice to move the teeth until they occupy a different relative position, likewise in accordance with the lock which in this case is to be actuated by the key.
For the displacement of the teeth, the body of the key on which one acts in the manipulation of opening or closing, is provided with a series of control elements or wheels which act on respective transmission means for the displacement of the teeth or notches with which the combination of the key is established. The means for moving the teeth includes at least one chain disposed in the interior of the stem and extending into the actuating body, the teeth attached to the at least one chain, at least one control wheel disposed in the actuating body and in meshed engagement with the at least one chain.
Although such a solution would be suitable from the point of view of the purpose aimed at, the inventor has been able to observe that it would present the following disadvantages:
It would be too complicated to make the key and its size would be far too big. PA1 It would be relatively difficult to achieve the correct relative positioning of the teeth in each case. PA1 Its manipulation would also be difficult because the very same insertion process of the key would bring about the tendency that the teeth would be displaced with regard to the original by established position, in spite of the step-by-step adjustment.